If the value of equilibrium constant for a particular reaction is 1.6 $$ \times $$ 1012, then at equilibrium the system will contain
A
mostly products
B
similar amounts of reactants and products
C
all reactants
D
mostly reactants.
Explanation
As, 1.6 × 1012 is very high value of K. Thus,
the reaction proceeds almost to completion and mixture must contain mostly products.
2
AIPMT 2015 Cancelled Paper
MCQ (Single Correct Answer)
Which of the following statements is correct for a reversible process in a state of equilibrium?
A
$$\Delta $$Go = $$-$$2.30 RT log K
B
$$\Delta $$Go = 2.30 RT log K
C
$$\Delta $$G = $$-$$2.30 RT log K
D
$$\Delta $$G = 2.30 RT log K
Explanation
$$\Delta $$G = $$\Delta $$Go + 2.303 RT log Q
At equilibrium, when $$\Delta $$G = 0 and Q = K
then 0 = $$\Delta $$Go + 2.303 RT log K
$$\Delta $$Go = – 2.303 RT log K
3
AIPMT 2015 Cancelled Paper
MCQ (Single Correct Answer)
The Ksp of Ag2CrO4, AgCl, AgBr and Agl are respectively, 1.1 $$ \times $$ 10$$-$$12, 1.8 $$ \times $$ 10$$-$$10, 5.0 $$ \times $$ 10$$-$$13, 8.3 $$ \times $$ 10$$-$$17. Which one of the following salts will precipitate last if AgNO3 solution is added to the solution containing equal moles of NaCl, NaBr, Nal and Na2CrO4?
A
AgBr
B
Ag2CrO4
C
Agl
D
AgCl
Explanation
From the Ksp values of the given salts calculate
the solubility values. Salt having highest solubility
will precipitate at last.
AgCrO4
⇌
2Ag+
+
CrO42-
s
2s
s
Ksp = (2s)2(s) = 1.1 × 10–12
$$ \Rightarrow $$ s = 0.65 × 10–4
AgCl
⇌
Ag+
+
Cl-
s
s
s
Ksp = s × s
$$ \Rightarrow $$ 1.8 × 10–10 = s
2
$$ \Rightarrow $$ s = 1.34 × 10–5
AgBr
⇌
Ag+
+
Br-
s
s
s
Ksp = s × s
$$ \Rightarrow $$ 5 × 10–13 = s2
$$ \Rightarrow $$ s = 0.71 × 10–6
AgI
⇌
Ag+
+
I-
s
s
s
Ksp = s × s
$$ \Rightarrow $$ 8.3 × 10–17 = s2
$$ \Rightarrow $$ s = 0.9 × 10–8
$$ \therefore $$ Solubility of Ag2CrO4 is maximum so, it
will precipitate at last.
4
AIPMT 2015
MCQ (Single Correct Answer)
Which one of the following pairs of solution is not an acidic buffer ?
A
CH3COOH and CH3COONa
B
H2CO3 and Na2CO3
C
H3PO4 and Na3PO4
D
HClO4 and NaClO4
Explanation
An acidic buffer is a mixture of a weak acid
and its salt with a strong base. Among CH3COOH,
H2CO3, H3PO4 and HClO4, the HClO4 is a strong
acid while all other are weak acid thus, HClO4 and
NaClO4 does not constitute to form an acidic buffer.
Questions Asked from Equilibrium
On those following papers in MCQ (Single Correct Answer)
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